Yesterday, I got message from Google that " Increase in server errors" and " Increase in not found errors" for my website in Webmaster Tools.

This is happens because, we migrated our website into new version from asp to aspx . So, our entire URL structure was changed and our back links also goes to 404 page. And, my 50% of traffic is also gone due to this new URL structure. So, I did 301 redirection for all old URL's(400 pages) to my new page like http://www.mywebsite.com/mypage.aspx to solve current issue of " Increase in not found errors" ..

But I would like to get my old SERP and PR's for my new pages to retrieve the same traffic..

So, please anyone let me know, if any valuable suggestions to retrieve my old traffic, PR and old rankings...

As mentioned by the other members, you are doing the right thing however you may have done it too late. You said you lost a lot of your traffic. Has it all returned to normal levels after your redirects? If not, time won’t make a difference. By redirecting URL’s, you should have seen immediate return to your previous traffic levels (assuming you redirected everything). If you let the site sit for too long without redirecting indexed URL’s, there is a chance that Google dropped them from the index because of their error status.

Also, you will not get all of your former PageRank from the redirects. 301 redirects pass diluted PageRank just like regular links do. For example I changed the URL on a website last year in a rebranding scenario and redirected all URL’s. At the beginning the site had a PR 5 and we ended up with a PR3 after all the dust had settled.

Also, you will not get all of your former PageRank from the redirects. 301 redirects pass diluted PageRank just like regular links do. For example I changed the URL on a website last year in a rebranding scenario and redirected all URL’s. At the beginning the site had a PR 5 and we ended up with a PR3 after all the dust had settled.

Shawn, I must say that's news to me. I'm under the impression that a 301 will result in the same link equity being passed as would be the case if the 301 wasn't present and the original URL was still in place.

I'm willing to admit I might be wrong about this. I read the article you mentioned. Perhaps the issue is the use of the term "passing page rank". What exactly does that mean? There's no question of a link or a 301 passing the actual page rank of the referring page. It passes a value that depends, in part, on the referring page's page rank, but it's usually "diluted" anyway, in the sense that it would normally be less than the actual numeric value of the page rank.

So maybe the issue is whether the value received by the directed-to page is the same as the value that would have been received from the original link. I believe it is, but I don't insist that I'm right. I'd be glad to hear your views.

Whatever the diluted percentage is in regular links, Cutt’s claims that its similar for 301 redirects. He mentions that they behave in much the same way as regular links in that a percentage of PR is passed on from the referring domain but not all of it.So, having a redirect (even if its on the same domain) wouldn’t pass on all PR. I take “passing PageRank” to mean that any link from one website to another is a sort of “vote” for the website receiving the link but that Google does not assign all authority to the site being linked to. They only give a little credit to that website as being one that is trustworthy or quality or what have you.

Thanks for that, Shawn. It's clearer now. I guess it's a matter of semantics. If you take "passing page rank" to mean giving a "vote" to the linked-to site, then I get the point.

Regarding Matt Cutt's video: no I didn't watch it. I dislike the whole idea of disseminating this sort of information in a video - something that Google seem to be doing more and more.

With a video, you have to find time to watch it, you usually have to watch it all the way through to get any benefit, and you have to watch it at a time and place where it doesn't disturb those around you. I find it much easier to simply read text off the page. That way, you can read it all at once or in small chunks as required, you can easily skip forward and back over bits you didn't understand, you can copy any important bits to other documents, you can search it, you can run it through a translator, and you can print it out to read on the bus.

Sorry, I didn't mean to use this post for a personal rant about videos. But I do find this attitude of Google annoying. They seem to think that we're too stupid to read words on the page, so they have to spoon-feed it to us in a video. (And maybe they're right.)